Conveying apparatus with endless chain means

ABSTRACT

Conveying apparatus provided with chain transmission means having an endless chain passing around a pair of sprockets, said chain transmission means further comprising an intermediate sprocket having involute teeth and disposed for meshing engagement with the endless chain on the tight side thereof, said intermediate sprocket being driven so as to move said endless chain.

United States Patent Hara et a1. [4 Apr. 25, 1972 54] CONVEYINGAPPARATUS WITH [56] References Cited ENDLESS CHAIN MEANS UNITED STATESPATENTS 1 Inventors: Takeshi Katsuta; Sholchi Nakao, 2,225,772 12 1940Dunlop ..198/l6 Mito; Katsuya Teranishi, Katsuta, all of 3,233,7212/1966 Redden..... ....198/14S Japan 2,633,354 3/1953 Mixer.... ..74/243[73] Assignee: Hitachi, Ltd., Tokyo, Ja 1,430,906 /1922 John ..198/16Filed: p l, 1970 FOREIGN PATENTS OR APPLICATIONS [2H App}. No: 24,753724,088 4/1932 France ..198/l6 Primary Examiner-Richard E. Aegerter 301Foreign Application Priority Data Amway-CW8 Apr. 4, 1969 Japan..44/25558 [57] ABSTRACT Conveying apparatus provided with chaintransmission means 1 1 "198/16, 198/203 having an endless chain passingaround a pair of sprockets, [51] Int. Cl ...Bg 3 8 65/28 said chaintransmission means further comprising an inter- 1 Field of Search 1mediate sprocket having involute teeth and disposed for meshingengagement with the endless chain on the tight side thereof, saidintermediate sprocket being driven so as to move said endless chain.

9 Claims, 6 Drawing Figures Patented April 25, 1972 3,658,166

3 Sheets-Sheet 1 INVENTOR 3 Wis/ll mm IM/Ml Mmm klraam mum/:1

BY d awwww ATTORNEY I Patented April 25, 1972 I 3,658,166

3 sheetse-sheet z CHA/N SPEED ATTORNEY 3 CONVEYING APPARATUS WITHENDLESS CHAIN MEANS The present invention relates to a conveyingapparatus provided with endless chain means, and more particularly to aconveying apparatus provided with endless chain means which mayconveniently be used in a moving path or an escalator by securing aplurality of step plates to said endless chain means.

In the past, an escalator or a moving path having endless chain meanshas been driven, for example as disclosed in United States Pat. No.2,649,181, by a motor connected to one of the sprockets around which anendless chain passes. However, since the tension in the endless chainamounts to a maximum value at the portion where the driving sprocketengages therewith, in the above mentioned known arrangement in which thechain is driven by only one driving sprocket, an endless chain of alarge capacity will be required where the moving path or the escalatoris long.

Recently, due to the big demand for buildings or other requirements, along moving path or a high-lift escalator has been made use of, and,therefore, a chain possessing substantial strength is needed.

However, in a moving path of an excessive length or in an escalator ofgreat height, a chain must be made, in order to obtain sufficientstrength, so as to have substantial dimensions, capacity and pitch,etc., so that the total dimension of the moving path or the escalator isuneconomically increased and the chain itself becomes expensive tomanufacture. Further, since a driving means for driving the sprocket isdisposed at one end of the moving path or the escalator, the effectiveconveying portion thereof must be greatly decreased.

An object of the present invention is to provide a novel driving meansfor an endless chain.

Another object of the present invention is to provide a conveyingapparatus having endless chain means in which a chain of small capacitycan be utilized.

A further object of the present invention is to provide a conveyingapparatus which can effectively be used over a long moving path or in anescalator of great height.

These and other objects of the present invention will be understood fromthe following description with respect to an embodiment of the presentinvention.

According to the present invention, there is provided a conveyingapparatus comprising a frame, at least one chain transmission meansmounted on said frame; each of said chain transmission means beingprovided with a pair of sprockets mounted at the opposite ends of saidframe, an endless chain passing around said sprockets, and at least oneintermediate sprocket having involute teeth and disposed between saidpair of sprockets for engagement with said endless chain on the tightside thereof; said apparatus further comprising means secured to saidendless chain for carrying loads to be conveyed, and means for drivingsaid intermediate sprocket.

An embodiment of the invention will now be described by way of examplewith reference to the accompanying drawings in which:

FIG. 1 is a diagrammatical side view of a moving path employing aconveying apparatus in accordance with the present invention;

FIG. 2 is an enlarged detailed view of the intermediate driving sectionin the conveying apparatus shown in FIG. 1;

FIG. 3 is a sectional view of the section shown in FIG. 2;

FIG. 4 is a diagram showing the relation between the chain speed andtime;

FIG. 5 is a diagram showing the relation between the distance of chaintravel and time; and

FIG. 6 shows a circuit for synchronizing the sprocket driving motors.

The conveying apparatus shown in the drawings comprises a pair of chaintransmission means which are mounted on a frame 1 and which arelaterally spaced apart in a relationship opposed to each other. In FIG.1 only one of the chain transmission means is visible. Each chaintransmission means has a driving sprocket 5 and an idle sprocket 6 whichare mounted at the opposite ends of the frame 1 and further has anintermediate driving sprocket 19 which is disposed between the drivingsprocket 5 and the idle sprocket 6. Each of the endwise sprockets 5 and6 has conventional teeth such as ASA teeth or DIN teeth and theintermediate sprocket 19 has involute teeth. The driving sprockets 5 and19 are driven by synchronized motors 2 and 16 respectively throughchains 3 and 17 and sprockets 4 and 18 respectively. An endless chain 7having a plurality of support rollers 9 is disposed so as to pass aroundthe sprockets 5 and 6. The apparatus may comprise one or more than threechain transmission means as the occasion demands.

A plurality of equally spaced step plates 8 are mounted to cross rods 15the opposite ends of which are secured to the support rollers 9 of thechain 7. The reference numeral 11 shows a sprocket which is coaxial withthe sprockets 4 and 5 and which is provided for driving a hand rail 14.The rotation of the sprocket 11 is transmitted through a chain 12 to ahand rail driving pulley 13 which in turn moves the hand rail 14 at thesame speed as the endless chain 7 and the step plate 8. The hand rail 14is stretched between the driving pulley 13 and an idle pulley 22. Theapparatus may have two hand rails which are laterally spaced apart in arelationship opposed to each other.

As clearly seen in the drawings, the sprocket 5 is disposed at one endas in a conventional arrangement and the sprocket 19 is disposed at aposition nearly intermediate between the sprockets 5 and 6 so as to meshwith the endless chain 7 on the tight or tension side thereof.

In this arrangement, the driving means provided at one end is the sameas a conventional one and the sprocket 5 has conventional teeth such asASA teeth. Therefore, due to the nature of the chain and sprocket, thechain speed slightly varies during every one pitch travel of the chainas shown by the curve A in FIG. 4. The line B in FIG. 4 shows theaverage chain speed.

FIG. 5 shows by the curve C the actual travel distance of the chain andby the line D the average travel distance.

In a sprocket having conventional ASA teeth or the like, such afluctuation of chain speed cannot be avoided. Therefore, in anarrangement where an intermediate drive sprocket has conventional teeth,the fluctuations of chain speed are duplicated and the chain issubjected to excessive tension unless the two drive sprockets rotate inthe same phase. Further,

in this type of arrangement, since there is some difference in pitchbetween the addendum and the dedendum of the teeth of the sprocket, theteeth of the sprocket intermittently engage with the roller of theendless chain so that a sprocket having conventional teeth cannot beused as an intermediate drive sprocket.

In the mechanism of engagement between a sprocket and the tight side ofan endless chain, only the order of one tooth of the sprocket isnormally in engagement with the chain roller and there exists asubstantial gap between the engaging tooth and a roller of the chain sothat, when the two driving sprockets in the aforementioned arrangementare driven at the same speed, at certain moments a tooth of theintermediate sprocket may possibly fail to engage with the chain roller.Thus, at some instants the intermediate sprocket may possibly be put ina condition wherein the driving force of the sprocket does not act onthe chain. As a result, the tension to be applied to the endless chainis entirely born merely by the endwise drive sprocket.

In view of these disadvantages, the present invention proposes to use asprocket having involute teeth as the intermediate drive sprocket 19 sothat it can drive the chain smoothly at a constant speed. According tothe present invention, the pressure angle between a tooth of theintermediate drive sprocket and a roller of the endless chain isselected to substantially zero degrees. Otherwise, smooth movement ofthe endless chain cannot be expected. Further, according to the presentinvention, the intermediate sprocket is so designed that the number ofengaging teeth is more than one at all times in order to ensurethesmooth operation of the endless chain. In a preferred embodiment of thepresent invention, the number of engaging teeth is one or two. With suchan arrangement, stable meshing engagement between the endless chain 7and the sprocket 19 can always be ensured, and the endless chain 7 canbe moved at a speed which is the same as the peripheral speed of thesprocket 19 on the pitch circle thereof. In other words, the chain canbe moved at a speed as shown by the line B in FIG. 4 and its traveldistance can be shown by the line D in FIG. 5.

Even with this arrangement, the fluctuations of the chain speed whichmay be produced by the end drive sprocket 5 may cause to some extentfluctuations in the tension of the chain. However, the extent of suchfluctuation of the chain speed is very small so that, in case where theendless chain 7 has a substantial length, the fluctuation of the chaintension is absorbed by the resiliency of the chain and no criticalproblems arise. Moreover, since the sprocket 19 is always maintained inengagement with the-endless chain 7, the fluctuation of the chaintension created by the end sprocket 5 will not be transmitted beyond theintermediate sprocket 19.

In the illustrated arrangement, when the chain 7 is driven in thedirection shown by the arrow in FIG. 1, the drive sprocket 5 shares theload imparted on the left hand half or the portion of the chain betweenthe sprockets 5 and 19, and the drive sprocket l9 drivesthe load on theportion and the return part of the chain.

Since the load on the left hand half of the endless chain is 1 notalways the same as that on the right hand half, the teeth of the drivesprockets 5 and 19 are not subjected to the same amount of force,however, if the driving speeds of the sprockets are always the same, theshare of the load by each sprocket remains unchanged. Therefore, it issufficient that the endless chain 7 has adequeate strength to bear thelargest of the above-mentioned loads.

In order to synchronize the chain drive speed of the drive sprockets 5and 19, the motors for the sprockets may be electrically connectedtogether so that the motor torque variation due to the load variation isdetected and utilized to synchronize the rotational speeds of themotors.

For example, as shown in FIG. 6, in order to synchronize two wound-rotortype three phase induction motors 2 and 16, the primary sides of themotors are connected together,and two phases of each motor arerespectively connected through the normal and reverse rotationelectromagnetic contacts 101a and 102a of an electromagnetic contactorto a three phase AC power source 103 while the remaining phase isdirectly connected to the power source. Further, the secondary sides ofthe motors 2 and 16 are also connected together and further joinedthrough secondary resistance contacts l04a of the electromagneticcontactor to common secondary resistances 105. The secondary resistances105 are short circuited at portions thereof by contacts 106a and 107a ofthe electromagnetic contactor. By this arrangement, the motors 2 and 16can be synchronized. The reference numerals 108 and 109 show mechanicalbrakes which can be released, when the motors are connected to the powersource, by the release coils which are connected to the primary sides ofthe motors.

The intermediate drive sprocket 19 is constantly in engagement with theendless chain 7 on the tight side thereof. However, for some reasons, ifthe force produced at the point of engagement acts to push the rollersof the endless chain 7 upwardly, the points of meshing engagement willbecome off the pitch circle of the sprocket resulting in inaccuratemeshing. Therefore, according to a preferable aspect of the presentinvention, as shown in FIGS. 2 and 3, there is provided an upperconstraining rail 20 as well as a lower guide rail for the supportrollers 9 one each being for every step plate 8. Moreover, another upperconstraining rail 21 is provided for the rollers of the endless chain 7in order to prevent the rising of the chain roller around the point ofengagement between the intermediate drive sprocket and the endlesschain.

In the illustrated embodiment of the present invention, only oneintermediate drive means is provided, however in the case where themoving path has a substantial length, a plurality of such intermediatedrive means may be used. Further, in the illustrated embodiment, aconventional end drive sprocket is used in combination with theintermediate drive means. In an application where any end drive meanscannot be employed, a plurality of intermediate drive sprockets havinginvolute teeth may be used in accordance with the present invention inorder to achieve the same purpose. Furthermore, in an application wherethe apparatus requires only one drive means, only one intermediate drivemeans may be used in accordance with the present invention. The presentinvention has thus been described with reference to one embodimentrelating to a moving path and it can also be applied to an escalator orto a conveyor without any difficulty.

What is claimed is:

l. Conveying apparatus comprising a frame; and at least one chaintransmission means mounted on said frame; each of said chaintransmission means including a pair of sprockets mounted at the oppositeends of said frame, one of said sprockets being a drive sprocket, theother being an idle sprocket, said drive sprocket and said idle sprockethave standard ASA teeth or DIN teeth, an endless chain passing aroundsaid sprockets, and at least one intermediate sprocket having involuteteeth and disposed between said pair of sprockets for engagement withsaid endless chain on the tight side thereof; means for synchronouslydriving said drive sprocket and said at least one intermediate drivesprocket, said apparatus further comprising means secured to saidendless chain for carrying the load to be conveyed.

2. Conveying apparatus in accordance with claim 1, which furthercomprises means provided at the portion of engagement between said atleast one intermediate drive sprocket and said endless chain forpreventing any rising movement of said endless chain.

3. Conveying apparatus in accordance with claim 1 wherein said means forsynchronously driving said drive sprocket and said at least oneintermediate drive sprocket comprise a pair of means, one driving saiddrive sprocket and the other driving said at least one intermediatedrive sprocket.

4. Conveying apparatus in accordance with claim 1 wherein said means forsynchronously driving said drive sprocket and said at least oneintermediate drive sprocket comprise a pair of motors electricallyconnected together so that motor torque variations due to loadvariations are detected and utilized to synchronize the rotationalspeeds of the motors.

5. A moving path or an escalator for conveying passengers, comprising aframe; and at least onechain transmission means mountedon said frame;each of said chain transmission means including a pair of sprocketsmounted at the opposite ends of said frame, one of said sprockets beinga drive sprocket, the other being an idle sprocket, said drive sprocketand said idle sprocket have standard ASA teeth or DIN teeth, an endlesschain passing around said sprockets, and at least one intermediatesprocket having involute teeth and disposed between said pair ofsprockets so as to engage with said endless chain on the tight sidethereof; means for synchronously driving said drive sprocket and said atleast one intermediate drive sprocket, and further comprising aplurality of step plates secured to said endless chain for carryingpassengers; and one or two hand rails driven at a speed which is thesame as the moving speed of said step plates.

6. A moving path in accordance with claim 5, which further comprisesmeans provided at the portion of engagement between said at least oneintermediate drive sprocket and said endless chain for preventing anyrising movement of said endless chain.

7. A moving path in accordance with claim 5 wherein said means forsynchronously driving said drive sprocket and said at least oneintermediate drive sprocket comprise a pair of means, one driving saiddrive sprocket and the other driving said at least one intermediatedrive sprocket.

8. A moving path in accordance with claim 5 wherein said synchronize therotational speeds of the motors. means for synchronously driving saiddrive sprocket and said 9. A moving path in accordance with claim 5wherein aid I at least one intermediate drive sprocket comprise a pairof drive sprocket and said sprocket have standard teeth motorselectrically connected together so that motor torque DIN teethvariationsdue to load variations are detected and utilized to 5

1. Conveying apparatus comprising a frame; and at least one chaintransmission means mounted on said frame; each of said chaintransmission means including a pair of sprockets mounted at the oppositeends of said frame, one of said sprockets being a drive sprocket, theother being an idle sprocket, said drive sprocket and said idle sprockethave standard ASA teeth or DIN teeth, an endless chain passing aroundsaid sprockets, and at least one intermediate sprocket having involuteteeth and disposed between said pair of sprockets for engagement withsaid endless chain on the tight side thereof; means for synchronouslydriving said drive sprocket and said at least one intermediate drivesprocket, said apparatus further comprising means secured to saidendless chain for carrying the load to be conveyed.
 2. Conveyingapparatus in accordance with claim 1, which further comprises meansprovided at the portion of engagement between said at least oneintermediate drive sprocket and said endless chain for preventing anyrising movement of said endless chain.
 3. Conveying apparatus inaccordance with claim 1 wherein said means for synchronously drivingsaid drive sprocket and said at least one intermediate drive sprocketcomprise a pair of means, one driving said drive sprocket and the otherdriving said at least one intermediate drive sprocket.
 4. Conveyingapparatus in accordance with claim 1 wherein said means forsynchronously driving said drive sprocket and said at least oneintermediate drive sprocket comprise a pair of motors electricallyconnected together so that motor torque variations due to loadvariations are detected and utilized to synchRonize the rotationalspeeds of the motors.
 5. A moving path or an escalator for conveyingpassengers, comprising a frame; and at least one chain transmissionmeans mounted on said frame; each of said chain transmission meansincluding a pair of sprockets mounted at the opposite ends of saidframe, one of said sprockets being a drive sprocket, the other being anidle sprocket, said drive sprocket and said idle sprocket have standardASA teeth or DIN teeth, an endless chain passing around said sprockets,and at least one intermediate sprocket having involute teeth anddisposed between said pair of sprockets so as to engage with saidendless chain on the tight side thereof; means for synchronously drivingsaid drive sprocket and said at least one intermediate drive sprocket,and further comprising a plurality of step plates secured to saidendless chain for carrying passengers; and one or two hand rails drivenat a speed which is the same as the moving speed of said step plates. 6.A moving path in accordance with claim 5, which further comprises meansprovided at the portion of engagement between said at least oneintermediate drive sprocket and said endless chain for preventing anyrising movement of said endless chain.
 7. A moving path in accordancewith claim 5 wherein said means for synchronously driving said drivesprocket and said at least one intermediate drive sprocket comprise apair of means, one driving said drive sprocket and the other drivingsaid at least one intermediate drive sprocket.
 8. A moving path inaccordance with claim 5 wherein said means for synchronously drivingsaid drive sprocket and said at least one intermediate drive sprocketcomprise a pair of motors electrically connected together so that motortorque variations due to load variations are detected and utilized tosynchronize the rotational speeds of the motors.
 9. A moving path inaccordance with claim 5 wherein said drive sprocket and said idlesprocket have standard ASA teeth or DIN teeth.